This was a very interesting chapter. Wilson's discussion of biophilia, habitat selection and the "savanna hypothesis" should generate some discussion here at booktalk. There were several studies(p 134-140) that Wilson referred to on these topics. Has anyone ever read about them before?

In case you'd like to participate in the discussion regarding habitat selection, but haven't read this chapter yet or studied human evolution, please read this post for a little background.

Biophilia is an appreciation for living things. It is believed by many that biophilia is an innate characteristic of humans.

Wilson seems to believe that the "savanna hypothesis" is correct. Some scientists do not believe that humans evolved in savanna environments or have an innate preference for habitats most resembling the savanna. I searched for and found an article discussing the "savanna hypothesis". Here is an excerpt...

"The global climate cooled and became drier between 8 million and 5 million years ago, near the end of the Miocene Epoch. According to the savanna hypothesis, this climate change broke up and reduced the area of African forests. As the forests shrunk, an ape population in eastern Africa became separated from other populations of apes in the more heavily forested areas of western Africa. The eastern population had to adapt to its drier environment, which contained larger areas of grassy savanna.

The expansion of dry terrain favored the evolution of terrestrial living, and made it more difficult to survive by living in trees. Terrestrial apes might have formed large social groups in order to improve their ability to find and collect food and to fend off predators

I am not sure how much hard evidence is behind the savanna hypothesis... but it seems that most scientist believe that an environmental change was necessary to drive evolutionary processes... when it comes to the question of why did some apes leave the forest, started to walk upright and think more intelligently... well, it is dificult to find all answers... I recall that my zoology professor had his own theory of why man started to walk upright. He said that there were mainly three reasons:1) Vision2) Pride3) Greed

Vision: Our ancestors did not eat only fruits like the other apes, but also rotten meat from dead animals. We were not able to kill big animals, and therefore we had to eat what the lions and the other animals left. In order to find such spots as quickly as possible, we had to look into the sky to see the birds that started to make circles around the dead animals. When we saw that, we started to run to reach that spot. For this purpose it was advantageous if we became a better vision and standing upright was one solution. Interestingly, the humans are very formidable long distance runners. In fact, there is no animal that can run longer distances than humans. Other animals can run faster, but only over shorter distances. Humans are able to run over 60km without stopping. We have also the advantage of sweating glands, and this cools us down. And running upright has also the advantage that we are less exposed to the sun, and therefore get less heated.

Pride:It is quite intriguing, but many animals have more respect for the animals that are taller. In biology, size matters. It means more power and more strength. Many animals that walk on four feet, also walk on two feets from time to time. For example, bears and Gorillas. This is often a means for impressing the enemy. For example, when gorillas or chimps want to show up, they walk upright and they hit their chest with their hands. They also make strong sounds. The capability of making vowels might also be related to this need of making sounds to impress the others. Thus, walking upright was a means to demonstrate a kind of herarchy and create some respect for the others. Our pride is still very marked and this has been one of the key ingredients for our evolution... but at the same time, this is also the reason why we are violent and make so many wars to those who damage our pride or do not respect us. Interestingly, still until our days we want to become taller for social purposes and higher status. For example, women wear heals not because they are more comfortable than normal shoes, but because they make them taller. Thus, when you see a fashion show with women dressing extravagantly with high shoes, you can recognise that we still carry the inheritance of the early hominoids who wanted to become bigger for pride.

Greed:When you observe the chimps and other apes you can recognise many types of behaviour that are very similar to ours. The social structure is also similar and the interpersonal relations follow similar patterns. Many antropologist believe that looking at the apes of today can give us many hints to the early stages of our ancestors millions years ago. Greed is a very important emotion, because it drives us to obtain more, and therefore makes us more competitive. It helps us to survive the struggle for life. When you put a big pile of bannanas near a group of hungry chimps, many of them will start to fight for the banannas. Eventually, a big male starts to dominate the others. He takes strategic position to defend the pile of bannanas, but when there are many other competitors, he will not be able to defend the whole bunch of fruits. While he counters one competitor from the left and keeps an eye on other from the right, another might come from behind and take some banannas. One strategy that many animals follow when there are many competitors and only one central source of food, is to take a piece to another place where you can eat it quietly. If you take a small piece, you divide the attention, and because the big bunch is still at the original place, noboby will follow you. Thus, the strategy is to be quick, take a big bunch, and then run away as fast as possible. Now imagine that if you walk on four feets, then you have only your mouth to carry your cargo. But then, if you walk on two feet, your hands are free to carry more. Thus, those apes that want more bannanas, they use their hands to take as much as possible, run away to quiet place and eat their bannanas. This behaviour is also observed with the chimps of today, that normally walk on four feets, but when they want carry a lot, they walk on two feet. Therefore, greed and the desire for more possesions might also driven the evolution of hominoids to walk upright.

Doc- Thank you for sharing what your professor taught you. In my classes at college I learned about the idea of vision pushing evolution toward walking upright. I had also learned about what you referred to as greed, presented to me more in terms of freeing-up the hands for activities. However, I had never heard of the theory involving pride. I agree, it is very intriguing. Of course I am sure that some combination of selection pressures resulted in walking upright. Like the old theory proposing that walking upright resulted from increase in brain mass, some ideas will be proven wrong, with new theories replacing them. I am always interested in these theories. If you hear of anything else, let me know.

Hi. I'm taking an advanced placement environmental science course in High School and have been reading The Future of Life. I am currently up to this chapter.

One of the questions I have to answer is: Do you buy into the savanna hypothesis?

If the savanna hypothesis means that humans evolved from apes like some of you seem to suggest, then I don't think I believe the savanna hypothesis. I guess I understand that humans are attracted to the savanna. Wilson wrote that when shown pictures of different environments, most children chose the savanna. He also said that Neolithic people cut down forests because they wanted their ancestral habitat, the savanna. Also, according to Wilson, most people prefer this sort of tree that originated in the African savanna. I personally don't think I prefer the savanna over any other environment.

Let me get this straight. The savanna hypothesis is implying that "humanity originated in the savannas and transitional forests of Africa."?

Quote:If the savanna hypothesis means that humans evolved from apes like some of you seem to suggest, then I don't think I believe the savanna hypothesis.

Just for that reason? Are you a believer in god by chance? You sound a bit like a creationist. Sorry if I am wrong.

Humans did not evolve from "apes", but chimps, gorillas and humans just may have eveolved from a common ancestor.

Good luck in your studies.

Mr. P.

But atheism is no more a religion than not playing chess is a hobby. - Robert Sawyer - Sci Fi Author

I'm not saying it's usual for people to do those things but I(with the permission of God) have raised a dog from the dead and healed many people from all sorts of ailments. - Asana Boditharta (former booktalk troll)

"The Sentient may percieve and love the universe, but the universe cannot percieve and love the sentient. The universe sees no distinction between the multitude of creatures and elements which comprise it. All are equal. None is favored...It cannot control what it creates and it cannot, it seems, be controlled by its creations (though a few might decieve themselves otherwise). Those who curse the workings of the universe curse that which is deaf. Those who strike out at those workings fight that which is inviolate. Those who shake their fists, shake their fists at blind stars." - Michael Moorcock in the "Queen of the Swords"

Well, if you opt to word it like that I guess I can say I don't "buy into" it. Buying into it implies somehow being duped or taken advantage of...and I'd hate to come right out and admit to either of the two.

Do I believe the savanna hypothesis is a reasonable hypothesis, or educated guess, as to explain why humans evolved the way we did? Yes, it seems to hold water. But then so do several other competing ideas. This is the fun part of science! Arguing and debating and trying to prove the other guy is wrong is what science is all about.

Do I "believe" it without reservation? Few scientists take such a leap of faith. They're trying their best to figure out our evolution and the savanna hypothesis has yet to be invalidated or proven false. But has it been proven valid? No.

Quote:If the savanna hypothesis means that humans evolved from apes like some of you seem to suggest, then I don't think I believe the savanna hypothesis.

It doesn't have anything to do with arguing that humans evolved from apes and neither does the theory of evolution. We evolved from a common ancestor - but not from them directly. The difference is better understood by envisioning a tree. Picture the trunk of the tree stretching up towards the sky. At some point along the trunk a branch shoots out to the left and reaches up for a few feet and then again this branch divides into two smaller branches. The two smaller branches represent modern humans and modern chimps, but they both are attached to the tree by a common branch. Make sense?

But this is all somewhat irrelevant. The savanna hypothesis is only one of many competing ideas about "why" we evolved and "how" our evolution took place. Do not mistake our ignorance for why and how for ignorance on whether or not we actually did evolve. There are very few scientists that argue against common descent or that humans didn't evolve from a common ancestor as the chimps. I'll take that last statement a step further and say that I don't know of any credible scientists that make such an argument. There are a boat load of creationists that argue these things left and right, but they are not respected in the science community and most have bogus degrees.

Quote:I guess I understand that humans are attracted to the savanna.

I think this is probably irrelevant. I'm attracted to just about everything beautiful, peaceful or majestic (including the mountains on Mars), but this doesn't mean I have origins in those things.

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